1. Field of the Invention
This invention relates to a method of and an apparatus for thermally recording an image or a thermo-sensitive recording medium by applying a coloring thermal energy of the thermo-sensitive recording medium.
2. Description of the Related Art
A thermal recording apparatus for thermally recording an image or the like on a thermo-sensitive recording medium is now widely in use. In particular, a thermal recording apparatus with a laser as a heat source, which can record an image at high speed, has been proposed (see Japanese Laid-Open Patent Publication Nos. 50-23617, 58-94494, 62-77983 and 62-78964, for example).
The present applicant has proposed a thermo-sensitive recording medium which is applicable to such a thermal recording apparatus and capable of recording a satisfactory image thereon, which includes leuco dyes, a developer and light-absorbing dyes extended on a support and develops color whose density varies in response to the thermal energy applied thereto (see Japanese Patent Application No. 3-62684 and Japanese Laid-Open Patent Publication No. 5-24219).
The thermo-sensitive recording medium, proposed by the applicant, has a thermo-sensitive layer formed on the support by coating it with an emulsion containing at least the developer, the light-absorbing dyes and a heat-fusible microcapsule containing at least leuco dyes, all dissolved and emulsified in an organic solvent which is insoluble or hardly soluble in water.
When an image or the like is recorded on such a thermo-sensitive recording medium, the humidity in the atmosphere in the thermal recording apparatus is not necessarily kept constant. When the humidity becomes high, the amount of moisture or water contained in the thermo-sensitive recording medium increases, and the sensitivity of the thermo-sensitive recording medium is enhanced. A problem has thus been pointed out in the conventional thermal recording apparatus that the sensitivity of the thermo-sensitive recording medium varies depending on the humidity, which makes it difficult to precisely record an image having a desired gradation.